Let A(t) be the area of a circle with radius r(t), at time t in min. Suppose the radius is changing at the rate of drdt=6 ft/min. Find the rate of change of the area at the moment in time when r=9 ft

The rate of change is ft^(2)/min

Step-by-step explanation:

The area of a circle is given by the following equation:

To solve this question, we have to realize the implicit differentiation in function of t. We have two variables, A and r. So

We have that:

.

We want to find

So

Since the area is in square feet, the rate of change is in ft^(2)/min.

So the rate of change is ft^(2)/min

15

step-by-step explanation:

we are given the following expression and we are to solve it and find the product:

-13 × (-5)

solving the given expression in the standard order of solving a mathematical expression, beginning with the opening of brackets and then multiplying the terms and changing their signs.

-3 × -5 = 15 (answer is positive because when negative is multiplied with negative, it gives a positive answer)